It was an effective cleaner and an even more effective fertilizer that fed toxic algae blooms in aquatic environments. Not the best choice unless you don’t have anything else.
Oxi-Clean is what I use 99.99% of the time. TSP is a rarity, and since the vast, vast majority of people here are never putting it in the drains, I don't think it's going to be the end of the world.
In areas with very hard water, it may be the only way to prevent calcium deposits that make dishes feel rough and fog glasses. An appropriate amount is < 1/8 of a tsp (~ 0.6 ml) per load.
It was an effective cleaner and an even more effective fertilizer that fed toxic algae blooms in aquatic environments. Not the best choice unless you don’t have anything else.